i've replaced the coil and the cdi, but this quad ('07 roketa 250 w/ vertical engine) will start immediately and run great----sometimes. other times it will put out a spark only at the end of the crank cycle. i've checked all the connections. sometimes when it's running it will die but restart without a problem. does this point to anything specific?

 

Do you have a kick start? If so, when it won't start, and you're getting that single spark when you let go of the start button, try the same thing with the kick start. Do you get only a single spark then too? If not, the trigger input wiring is suspect.

But we're getting too far ahead. How many pins on your CDI? 6 pins (a 4 pin and a 2 pin connector)? Do you know if your CDI is DC powered or AC powered?

Once these questions are answered we can pick the right procedure to use. But we have to proceed carefully. Your problem is intermittent, and intermittents are tough. That means that all diagnostic tests have to be done when the quad is not starting up. You must verify that the quad won't generate steady spark, do the tests, then verify that the quad still does not generate steady spark. If you don't bracket the tests on both ends (verifying the the problem was, and is still there) then you won't know which tests were done while the quad was working and which were done with it not working.